The fourth season of Enterprise concludes the unpopular Temporal Cold Warstory arc that had been a staple of the series since "Broken Bow". The remaining episodes of season four refocus Enterprise on the series' original prequel concept by exploring cultural shifts on Vulcan; establishing the beginnings of conflict between Earth and the Romulans; explaining the difference in appearance between the Klingons of The Original Series and those of The Next Generation; and exploring the obstacles humanity must overcome before allying with alien species.

Season 4 saw the series move to Fridays at 8pm EST, and Manny Coto stepped up to become show runner and Executive Producer. Judith and Garfield Reeves-Stevens were brought on as story editors. After the narrow escape from cancellation at the end of season 3, and despite continued fan campaigns, the series was officially cancelled on February 2, 2005.

For the fourth season, UPN reduced the allowed budget from $1,7 million to $800,000 per episode. One of the most significant results of the budget cut was the series now being shot on digital instead of film.

John Billingsley felt that this season was the strongest overall of the shows run, and credited the new format for this success. "I think the idea of having the multi-episode arcs was the best way of having your cake and eating it too, getting some kind of a sustained narrative drive which you can't do in any standalone episodes, and not necessarily tying up a whole season the way we did in season three when we were chasing the Xindi." On the cancellation at the end of the season, Billingsley remarked, "I think if anything what I would love fans to come away with is a sense of the show was getting better and while it was disappointing we didn't [get] a full seven year run we [were] beginning, I think, to establish ourselves as a strong series in our own right." [1]